Modular multizone zone logic control center

ABSTRACT

A control system for utilizing a single, low voltage thermostat to actuate a plurality of heating means or a plurality of cooling means.

United States Patent [191 Callahan June 28, 1974 1 MODULAR MULTIZONEZONE LOGIC CONTROL CENTER I [56] References Cited [75] Inventor: GeorgeC. Callahan, Liverpool, UNITED STATES PATENTS 3,242,978 3/1966 McGann165/25 [73] Assignee: Carrier Corporation, Syracuse, NY.

- Primary ExaminerCharles Sukalo [22] 1972' Attorney, Agent, or Firm-J.Raymond Curtin; Donald [2]] Appl. No.: 306,966 F. Daley Related US.Application Data [62] Division of Ser. No. 131,153, April 5, I97], Pm.N0. [57] ABSTRACT 3,709,769- A control system for utilizing a single,low voltage thermostat to actuate a plurality of heating means or a [52]US. Cl. 165/2, 165/26 plurality f cooling means, [51] Int. Cl. F25b29/00 58 Field of Search 165/2, 25, 26; 236/1 B 1 01mm, 3 DrawlngFigures MODULAR MULTIZONE ZONE LOGIC CONTROL CENTER CROSS REFERENCE TORELATED APPLICATION BACKGROUND OF THE INVENTION In many air conditioninginstallations, the room thermostat is utilized to control a plurality ofdevices such as gas valves, motor contactors or relays, solenoid valves,etc. To simplify the air conditioning installations, it is desirable toutilize a low voltage control circuit. However, the number of devicessuch as valves and relays which can be controlled by a single lowvoltage circuit is limited.

For example, many air conditioning installations utilize a 24 volt classII control circuit as defined by the National Electric Code. For a 24volt circuit, current may not exceed 3.2 ampe'res. As a matter ofpractice, most circuits are designed with a 40 VA maximum or statedanother way, maximum current is ordinarily restricted to 1.66 amperes.Further, the thermostats ordinarily employed in air conditioning controlsystems are designed for low current flow therethrough.

As a result, many air conditioning systems employing a number of relaysand valves which must be controlled by'a single thermostat utilize linevoltage for the control circuit. Special line voltage thermostats,relays and valves are employed in line voltage control circuits. Thisincreases both installation and component costs.

SUMMARY OF THE INVENTION This invention realtes to a control system fora heating and cooling apparatus employing a plurality of cooling meansfor cooling air and a plurality of heating means for heating air, atleast two of the cooling means and at leasttwo of the heating meansbeing adapted to serve a single zone, the control system includingtemperature responsive means located in one of the zones served by theheating-cooling apparatus, the temperature responsive means beingconnected to a first control circuit which includes means for supplyingelectrical current thereto. A first electrically actuated control meansin the first control circuit is provided to energize first cooling meansto supply cool air to the zone served by the temperature responsivemeans. A second electrically actuated control means in the first controlcircuit is provided to energize first heating means to supply heated airto the zone served by the temperature responsive means.

A second control circuit including means to supply electrical currentthereto is provided with a third electrically actuated control meansadapted to be energized by the first control means to energize secondcooling means to supply cool air to the zone served by the temperatureresponsive means. A fourth electrically actucircuit, the fourth controlmeans being energized by the second control means to energize secondheating means to supply heated air to the zone served by the temperatureresponsive means.

'ated control means is provided in the second control BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a plan view of an air conditioning apparatuswith portions of the cover broken away to illustrate internalcomponents;

FIG. 2 is a view partly in section and partly in elevation of theapparatus of FIG. I; and

FIG. 3 is a schematic view of the control system for the airconditioning apparatus of FIGS. I and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thereis illustrated an air conditioning apparatus adapted to serve aplurality of zones in a building to provide individual temperaturecontrol in each zone without the use of dampers, damper actuators, etc.A plurality of direct-fired heat exchangers 2 for heating air and aplurality of refrigerant coils 4 are provided. A fan 6 and fan motor 7are provided to circulate air over the evaporator coils and heatexchanger. Suitable switch means 8 (FIG. 3) are provided to complete theelectrical circuit to fan motor 7 to energize the motor.

The unit illustrated is adapted to serve up to five individual zones. Toaccomplish this, baffles 9 are located to provide five separate airpassages downstream from fan 6. Each passage contains a singlerefrigerant evaporator coil 4 and two direct fired heat exchangers 2.While a single evaporator coil and two direct-fired heat exchangers areillustrated in each air passage, it should be understood that anydesired number of evaporator coils 4 and-heat exchangers 2 could belocated in each passage formed by baffles 9. Further, electricresistance elements or other well-known types of heating means could beemployed in place of the direct-fired heat exchangers 2. Each airpassage is provided with a discharge opening 10, only one of which isvisible in FIG. 2.

The conditioned air from each discharge opening 10 may be supplied tothe individual zone to be served thereby. While each passage containingan evaporator coil 4 and two heat exchangers 2 may serve a single zone,in many applications a number of discharge openings may be connected toa common duct to serve a zone requiring a greater heating and coolingcapacity than could be provided by a single evaporator coil and two heatexchangers.

Each heat exchanger 2 is provided with a fuel burner 12 and a fuel valve14 adapted for energization by thermostatic control means located ineach zone served by the air conditioning apparatus.

A refrigerant compressor 16 and a condenser 18 are provided to supplyliquid refrigerant to the evaporator coils 4. Each evaporator coil 4 isprovided with a refrigerant liquid line solenoid valve LLS (FIG. 3) tocontrol the flow of refrigerant from the condenser 18 to the coils. Theliquid line solenoid valves LLS are also controlled by thermostaticcontrol means located in each zone served by the air conditioningapparatus. Fan means 20 are provided to circulate ambient air overcondenser 18 to condense the refrigerant therein.

Air from the individual zones is returned to the apparatus throughopening 22 into a chamber 24. Fan 6 draws air from chamber 24 throughfilter 37 for passage over heat exchangers 2 and evaporator coils 4prior to passage to the individual zones.

FIG. 3 illustrates a control arrangement for the aforementioned airconditioning apparatus for an installation wherein the apparatus isadapted to serve two zones, one zone being served by a single evaporatorcoil 4 and the two heat exchangers associated therewith, the second zonebeing served by the remaining four evaporator coils 4 and the eight heatexchangers 2 associated therewith.

Thermostatic control means including temperature responsive switch 40and temperature responsive switch 42 is disposed in the zone served by asingle evaporator coil 4. Thermostatic control means 17, which includestemperature responsive switch 44 and temperature responsive switch 46,is disposed in the zone served by the remaining four evaporator coils.The thermostatic control means 15 and 17 are both connected in a firstcontrol circuit provided with 24 volt current by a transformer 48. Thetransformer 48 provides power to energize control relays A/2 and 8/3,gas valves 50 and 52 and a gas valve relay C/l including normally openswtich Cl. Relay A/2 includes normally open switches Al and A2. RelayB/3 includes normally open switches B1, B2 and B3. The total currentrequirement of the relays, gas valves and heat anticipators 54 withinthermostatic control means 15 and 17 in the first control circuit isbelow the current limitations of standard thermostatic control means,thereby allowing the use of a mass produced, low cost thermostat.

To energize additional relays and gas valves in response to thermostaticcontrol means 17, a second control circuit including transformer 56,control relays D/2 and EB, gas valves 58 and 60 and a gas valve relayF/l is provided. Relay D includes normally open switches D1 and D2.Relay E/3 includes normally open switches El, E2 and E3. Relay F/lincludes normally open switch Fl. Relays D/2 and E/3 are energized bythe closing of switch B1. Gas valve relay F/ l and gas valves 58 and 60are energized by the closing of control relay switch C 1. The relaysD/2, E/3 and F/l and gas valves 58 and 60 which are energized bytransformer 56 increase the number of relays and valves controlled bythermostatic means 17 without increasing the current flow throughthermostatic switch contacts 44 and 46.

To energize an even greater number of relays and gas valves in responseto thermostatic control means 17, a third control circuit includingtransformer 62, control relay G/2 and a gas valve 64 is provided. RelayG/2 is energized by the closing of switch E1. Gas valve 64 is energizedby the closing of relay switch Fl.

When heating is required in the zone served by thermostatic controlmeans 15, the heating-cooling switch 66 is moved to the heating positionas illustrated by the dotted line to provide current to thermostaticswitch 42. Upon a drop in the temperature of the zone, switch 42 willclose to provide current to gas valve 50 and provide gas to the burnersassociated therewith to provide heat to the zone.

When heating is required in the zone served by thermostatic controlmeans 17, the heating-cooling switch 68 is moved to the heating positionas illustrated by the dotted line to provide current to thermostaticswitch 46. Upon a drop in the temperature of the zone, switch 46 willclose to provide current to gas valve 52, and gas valve relay C/l. Gasvalve relay C/l will in turn close switch C1 to provide current to gasvalves 58 and 60 and gas valve relay F/l, thereby closing switch F1 toprovide current to gas valve 64.

It can be seen from the foregoing that thermostatic switch 46 controlsgas valves 52, 58, 60 and 64 to energize the eight heating sections 2serving the zone containing the thermostatic control means 17.

When cooling is required in the zone served by thermostatic controlmeans 15, the heating-cooling switch 66 will be positioned as shown bythe solid line to provide current to thermostatic switch 40. Upon a risein temperature of the zone containing switch 40, the switch will closeto provide current to relay A/2. Encrgization of relay A/2 will closeswitches Al and A2 thereby providing current to the liquid line solenoid70 to open the valve and allow passage of liquid refrigerant fromcondenser 18 to the coil 4 serving the zone containing thermostaticcontrol means 15.

Relays H/l and 1/1 will also be energized by the closing of switch Al;energization of relay H/l closing switch H1 to energize the compressor16, energization of relay J/1 closing switch J1 to energize condenserfans 20. Thus, upon a demand for cooling, the compressor and condenserfan will be energized and the liquid line solenoid valve 70 will beopened to allow passage of liquid refrigerant from the condenser to theevaporator coil 4 serving the zone containing themiostatic control means15.

'When cooling is required in the zone served by thermostatic controlmeans 17, the heat-cool switch 68 will be moved to the positionillustrated by the solid line in FIG. 3 to provide current tothermostatic switch 44. Upon a rise in temperature of the zonecontaining thermostatic control means 17, switch 44 will close andenergize relay B/3. Energization of relay B/3 will cause switches B1, B2and B3 to close. Closing of switch Bl will complete a circuit throughrelays D/2 and E/3 which will in turn cause switches D1, D2, E1, E2 andE3 to close. Closing of switch E1 will provide current to relay G/2which will close switches G1 and G2.

Thus, energization of relay B/3 will cause the subsequent energizationof relays D/2, E/3 and G/2 and the switches associated therewith toenergize relays H/l and J/] and open liquid line solenoid valves 72, 74,76 and 78. Energization of relays H/l and 1/1 will close switches J1 andH] to complete a circuit through the condenser fan motor and thecompressor to provide high pressure liquid refrigerant through opensolenoid valves 72, 74, 76 and 78 to the evaporator coils 4 to cool theair passing thereover.

It can be seen from the foregoing that control relays, energized by thethermostatic control means, are utilized to energize a second controlcircuit containing control relays which, if desired, can be utilized toenergize a third control circuit. This control arrangement may beemployed to energize a plurality of circuits, all controlled by a singlethermostatic means which is required to carry a small fraction of thetotal current employed in the entire control system. Further, the numberof relays or other electrical control devices in each control circuitmay be selected to limit the current flow in each circuit while allowingan unlimited number of devices in the control system to be energized bya single thermostatic means simply by increasing the number ofindividual control circuits.

While I have described a preferred embodiment of my invention it is tobe understood that the invention ing the low voltage circuit in responseto the temperature sensed;

supplying heated or cooled air to the zone in response to activation ofthe low voltage circuit;

activating additional low voltage circuits in response to activation ofthe low voltage temperature sensing circuit; and

supplying heated or cooled air to the zone associated with each lowvoltage circuit in response to the activation of the additional lowvoltage circuits. l

1. In a multizone heating and cooling system a method of utilizing lowvoltage, low power control circuits to control the temperature in aplurality of zones from the temperature sensed in one of the zonesincluding the steps of: sensing the temperature in a first zone with alow voltage temperature sensing device in a low voltage electricaltemperature sensing circuit, and activating the low voltage circuit inresponse to the temperature sensed; supplying heated or cooled air tothe zone in response to activation of the low voltage circuit;activating additional low voltage circuits in response to activation ofthe low voltage temperature sensing circuit; and supplying heated orcooled air to the zone associated with each low voltage circuit inresponse to the activation of the additional low voltage circuits.